In many systems, data is transmitted or retrieved asynchronously, i.e., without any additional timing reference. However, the receiver or detector in the system must eventually process the data synchronously. To do this, the receiver or detector must recover the timing information (e.g., the “clock”) from the data at the receive end.
Timing recovery is becoming a major challenge in data storage channels, such as in disk drive storage systems. As storage capacities and data rates increase, design tradeoffs may require that the storage channels operate in a noisier environment with higher raw error rates. However, more noise and more raw detection errors may make reliable timing recovery more difficult.